Optimal Relay Deployment in Bidirectional AF Relaying Systems

Recently, the node deployment problem of a relay network has brought a hot discussion. This paper studies utility function minimum maximization problem of bidirectional amplify and forward relaying systems from the perspective of relay deployment. Since many optimization problems are considered separately, different algorithms are proposed for each optimization problem. So we consider a unified utility function instead of the separate optimization goals. Two different optimization problems are considered. One is to find the optimal relay deployment and optimize the utility function with fixed power allocation. The other is joint optimization of relay deployment and power allocation. Especially when power is fixed, the relay deployment is not a fixed location, but a piecewise function. In order to balance the two opposite transmission directions in bidirectional relaying networks, the relay deployment is related to channel gain and path loss. In addition, approximate and accurate expressions of average relay deployment are investigated when only statistical channel information is available. Simulation results validate that the reasonable relay deployment improves the system performance.